Baidu, China's largest search engine, launched a migration map on Sunday that shows the travel routes used by people during the 40-day Chinese Lunar New Year festival known as Spring Festival—the world's biggest annual human migration. This year, New Year's Day is Jan. 31, which marks the beginning of the Year of the Horse. The annual migration kicked off Jan. 16.

Baidu says the map (hat tip WSJ''s China Real Time) was created using data taken from users of its location-based applications to calculate and analyze the mass migration of the population during the Spring Festival. The map shows the travel routes and their popularity.

The interactive map allows users to click on a particular city to see the inflow and outflow of travelers during a particular time period (see below). The seasonal migration routes show huge outflows of people from urban areas to inland provinces, where many of these folks are originally from.

For example, on Tuesday the map showed Beijing as the No.1 city for arrivals and departures.